Abstract: Two different specifications of diffusion pump oils were obtained by distillation cutting through petroleum base oil by using molecular distillation technology. The two kinds of diffusionion pump oils are then subjected to full-scale distillation, and the data obtained after cutting the two-stage and five-stage fractions. The experimental results show that the diffused pump oil fully distilled has a narrow distillation range, a smaller slope and a narrower distillation range. We found that the light fraction and heavy fraction contained in the diffusion pump oil are less, the mixed components are relatively uniform, and the ultimate vacuum is higher. After cutting two and five fractions, kinematic viscosity distribution is uniform, which indicates that the mixed components in the diffusion pump oil are uniformly distributed and the purity is higher.

Key words: ultimate vacuum, diffusion pump oil, vacuum pump, base oil, fraction, molecular distillation